As the term suggests, a hybrid electric drive is a combination of electrical propulsion and a conventional fuel burning engine, usually a diesel. This combination has several advantages.

Compared to a electric vehicle, the hybrid electric vehicle (HEV) has more range, and often does not have to carry as many bulky battery cells.

Compared to a conventional vehicle the HEV uses its fuel more efficiently and economically, and this produces less pollution. Often the engine is run at a low output sufficient to keep the batteries charged. Output can easily be increased when there is a need for more power.

When the vehicle is not being used the batteries can be charged by plugging the vehicle into the national power supply grid. Systems such as wind, solar and hydro-electric power can be utilized

Ralph Zumbro, Author of "Tank Sergeant", writes about the Hybrid drive M113 that United Defence have built:-

"Phil, The one I was in, and it may be the only one, is state of the art. They steer it with a Bradley gunner's control and it will run for an hour at 30mph on two batteries which are in boxes sized approximately 18"x36"x48". Then a standard issue genset cuts in. The motors are rated at 250 hp each and are oil cooled. It is weird to see a 3 inch diameter drive shaft coming out of a motor the size of a 5 gallon can. The rubber tracks are soundless, and they've got 2500 miles on them with very little wear showing. That adds up to a VERY quiet vehicle for recon work. Put electric motors, rubber tracks and a two man turret with a 30mm gatling weapon on a standard 113 hull and you've got a recon Tankita. I mentioned to the people at United Defense that not needing air for the engine made the vehicle capable of running around UNDER water and was told that that had been thought of. That means that you could add enough armor to stop larger weapons, as long as you don't compromise the mobility." Acceleration of the HED M113 is FIVE TIMES faster than that of a standard M113A3!

Ralph was also responsible for making me aware of the Capstone Turbine.

(Hybrid Electric propulsion) " has MUCH to recommend it. First is efficiency. From the Belgian Cobra to the UD electric M113, they run about 20% more fuel efficient than normal drives. This is due to two factors. First the engine can be tuned to a constant RPM, second, the acceleration shocks are taken by the batteries. Batteries, of course, allow the user to tailor the vehicle's battery operation to specs. It is possible to create an All electric with rubber band tracks that has NO heat signature when on batteries. This would be the scout version. Most important, to me, is the coming age of electric weaponry from lasers through direct energy, including plasma, to electronic and sonic weaponry. I am going to use the UD base for my Tankita, although I understand the South Afrikaners have a genset so small that it fits INSIDE the flywheel housing. The electric also allows mounting the engine anyplace its weight would do the most good. Under the gun cupola in an APC for instance. As a last item, try typing in Capstone Turbogenerators. They are an outfit in California who have coupled a turbine to an armature and effectively have ONE moving part. The armature is motored to get the turbine/compressor part up to speed and then the fuel is fed in. Neat". The key word under Capstone, using Google is "Rosen Motors". They are actually under construction and selling.

HEVs are no longer just interesting experimental vehicles, they are viable alternate propulsion systems, and one that offers several advantages to the military. Many of these vehicles are of at least 24,000lbs weight, which suggests that there is no reason why an M113 with a Capstone turbine could not be fielded now.

Personally I think the best place to mount this is in the centre of the infantry compartment. The troops can stand on it when using the roof hatch or sit on it to face outwards to use firing ports (which some versions of the M113 have, such as the Korean KIFV). The dimensions of the Capstone HEV turbine suggest that this is a quite practical arrangement.

In fact it may be possible for the M113 to mount a pair of turbines, even though only one appears necessary. This would give a welcome measure of redundancy and plenty of extra power should it be needed always a useful thing on a military cross country vehicle. Removing the engine from its traditional position at the front would also free up room for a bow gunner. It might even be possible to have a gunner on each forward corner.

Ralph comments:- Phil; In normal 113 configuration, the troop bench is directly over the tracks, however, the engine/generator would fit rather nicely right under a one man turret, with access hatches on the sides of the enclosure. A Capstone turbine would do it, with a fuel cell farther down the line.

PW: So the Gunner can stand on it to use the .50/mk19/30mm ASP? -I like that better, since it means you can still use the rear of the compartment for cargo/bulky loads etc. If we are redesigning, I'd have two cupolas, like the KIFV

FEEDBACKErik Manders writes:- Hagglunds apparently has a working prototype HEV APC. They've taken things to the logical extreme of separating the power/crew, drivetrain and payload modules. Since they seem to be developing both wheeled and tracked drivetrain modules, this allows a lot of specialist tailoring flexibility. See http://www.haggve.se/pageopen.asp?Pid=12 for more info.

UPDATE Diesel fuel itself can be produced from sources other than fossil fuels. Biodiesel can be made from vegetable oil.

UPDATERalph Zumbro Now everybody is getting into the hybrid bandwagon, right up to 10 ton trucks and Personel carriers. Oshkosh trucks, for instance, has one that even uses a reversable fuel cell as a battery, and if I heard him right, the man from UD sez that on Lithium ion batteries, their latest hybrid 16 tonner will do 10 hours at 45kph? Gotta check that out later. This is getting REAL interesting. Putting those motors and batteries along with would you believe turbine powered alternators in any legacy vehicle changes the whole ballgame. Drop some of this in a tankita and you've suddenly got continental cruising range.

The Chinese have been using Biodiesel for decades. I have done extensive research on the subject, and you can make the infernal combustion burn anything....The problem is this....Every acre or hectare you put under sovbean, Jojoba, or corn production for fuel use, is OUT of the food producing business. In other words, a balance has to be struck, feed 'em or fuel 'em. Type the word Pyrolysis, into Google and watch what comes up. The basics are that if anything that was once alive, to include dead bodies, it heated to about 430°C (800°F). at a pressure of about 1000psi, in a non-oxygen atmosphere, it will convert to Crude Oil. The rate is one ton of garbage, hippies, old tyres, manure, etc will produce two barrels of crude, one barrel of water and about 250lb of imiscible solids suitable for paving.

RZ: The efficiency factor for the infernal combustion engine runs around 18%--23% There are some small mechanical and parasitic losses, but over 70% of the 188,000 BTU in every gallon of fuel is simply blown off as waste heat. There, however, is the heat source for a Pyrolysis plant. Simply run the exhaust of a genset through the garbage cooker, stuff in your biomass and fire up. My research says the best use for the Pyroplant is to convert the waste to oil, and then use the residual heat to simply distill the resulting good grade of crude into benzene, gasoline, kerosene, Diesel, etc, using modern knowledge on an old fashioned 1940s oil distillery. KISS. ANY heat from a vehicle engine can be converted to electricity using the Peltier effect (thermocouple) and added to the Hybrid electric system's batteries. The Rooskies even managed to run an old tube type radio off of a kerosene lamp, up in the arctic.

Jane's Armour and Artillery Upgrades 1996-97 has some information on United Defense's Hybrid Electric Drive Demonstrator (HED-D) vehicles based on the M113 and Bradley.The HED-D :-  .......has an infinitely variable transmission which means that the driver does not have to select gear. This allows full power over the entire engine speed for greater acceleration and slope climbing......Engine speed can be controlled independently of the vehicle speed and will run at a more constant speed for better fuel economy...... Manoeuvrability and steering will also be improved as each track is controlled independently with track speed being controlled throughout the turn.